NYC Women's Machine Gun Squad Police Reserves 1918

I stumbled on this image and one other (http://i.imgur.com/CuFHh0w.jpg) while digging through the National Archives for our show on WWI small arms.
I found it interesting as at first I believed these guns to be spill over from the US contracts that never made it to Europe, but on closer inspection it appears to be the older 1914 pattern and is likely chambered in .303 British.
These were probably from the earlier US government tests of the guns, before the successful transition to 30-06, somehow handed down to law enforcement.